1. Field of the Invention
This invention relates to a hydraulic controller for controlling the operation of a plurality of hydraulically operated devices in a predetermined sequence of individually adjustable timed intervals of operation for each such device. Machine operations, operated by such hydraulically operated devices, may be controlled in predetermined sequence with the timed interval of each given operation being controlled by corresponding control members of the controller which are individually adjustable for varying the length of intervals of operation for each of the machine operations.
2. Description of the Prior Art
Various types of control devices have been developed heretofore for controlling the operation of pilot valves, switches and other similar devices. Examplary of such controllers are the prior U.S. Pat. Nos. 3,404,227; 3,428,085 and 3,444,896. In these prior controllers, means have been provided for controlling the operation of associated pilot valves or switches in response to the operation of electrical motors, pneumatic motors and hydraulic motors. However, none of these devices have been found to be acceptable, or suitable, for use in controlling the operation of hydraulically operated devices such as are present in many presently used complex machines used in various production operations. By way of example, various known machines are employed in performing injection molding vacuum forming, blow forming, rotational molding and similar production operations which require the operation of various hydraulically operated mechanisms in a predetermined sequence. Generally, the hydraulic ram and cylinder utilized for opening and closing molds, moving turrets, etc. are in turn operated by hydraulically operated pilot valves. Such pilot valves typically are in turn operated by various solenoids, relays and associated electrical circuitry. The typical system for operating a complicated vacuum forming machine, or the like, usually includes a very complex electrical and hydraulic system including a large number of such relays, solenoids, pilot valves, etc. in addition to the main operated hydraulic devices performing the machine operations.
In view of the foregoing, it has been recognized that there is a real need for a hydraulically operated control device, suitable for being powered from the hydraulic fluid supply of the machine, for directly operating the various hydraulically operated devices of the machine which are performing the machine operations. Such a hydraulic controller would eliminate the necessity of complicated electrical circuitry, solenoids, relays and other associated electrical equipment as well as the inherent time delay attendant the necessary step-by-step operation of such components in a complicated electrical system. It has further been recognized that such hydraulic controller should be relatively easy to operate and should provide for the operation of the various machine operations in timed intervals, in a predetermined sequence and wherein the individual machine operations can be operated for selectable intervals of operating time.